Multi-operation laser tooling for deposition and material processing operations

ABSTRACT

Disclosed herein are methods, apparatus, and systems for a multi-operation optical beam delivery device having a laser source to generate the optical beam. A beam characteristic conditioner that, in response to a control input indicating a change between the different laser process operations, controllably modifies the beam characteristics for a corresponding laser process operation of the different laser process operations. A delivery fiber has an input end coupled to the beam characteristic conditioner and an output end coupled to a process head for performing the corresponding laser process operation.

RELATED APPLICATIONS

This application is a continuation-in-part of each of the followingapplications filed May 26, 2017: U.S. patent application Ser. Nos.15/607,399; 15/607,410; and 15/607,411; and International ApplicationNo. PCT/US2017/034848. Each of these applications claims benefit of U.S.Provisional Patent Application No. 62/401,650, filed Sep. 29, 2016. Allof these applications are incorporated by reference herein in theirentireties.

TECHNICAL FIELD

This disclosure generally relates to laser deposition. Moreparticularly, this disclosure relates to a multi-operation laser (e.g.,one having a controllable spot size, divergence profile, spatialprofile, beam shape, or the like, or any combination thereof) forachieving multiple laser processing tasks using a single tool.

BACKGROUND

Deposition of materials (wire, powder, or strip) using lasers isinherently a process that produces low-tolerance features, or it may beintentionally low tolerance to increase throughput or deposition rate atthe cost of feature resolution. To further refine a low tolerance finishor develop other desired features, further processing of artifacts leftover from a previous additive process is sometimes performed duringsubsequent removal, smoothing, refining, ablation, or machiningoperations. Such subsequent processing operations have sometimes used aseparate machine to perform material removal by methods involvingmechanical post-processing, chemical treatment, or thermal treatment(e.g., by application of heat). Separate machines for such operationscan add, among other things, production delay, tooling cost, andtraining burden.

Patent Application Pub. No. US 2009/0283501 A1 of Erikson et al.describes a laser deposition apparatus for preheating a workpiece priorto deposition. The cross-sectional width of a beam is increased anddecreased for, respectively, preheating and deposition by moving opticalcomponents housed in a deposition nozzle—close to the operatingenvironment and potentially susceptible to debris, among otherdeficiencies.

SUMMARY

The present inventors have recognized that performing additional laserprocessing with the same laser tool used for laser-assisted deposition(or simply, deposition) enhances speed and efficiency. Accordingly, insome embodiments, a laser source and beam characteristic conditionerspaced apart from a process head may be used to deliver adjustable beamstailored for different processing operations. Furthermore, amulti-operation optical beam delivery device described herein includes ameans by which to largely (i.e., subject to practical physical andimplementation-specific limitations) decouple spatial and angulardistributions so that they are not constrained by a reciprocalrelationship.

A multi-operation optical beam delivery device facilitates differentlaser process operations by modification of beam characteristics of anoptical beam. The different laser process operations includes laserdeposition and processing of a deposition region. The device has a lasersource to generate the optical beam, a beam characteristic conditioner,and a delivery fiber. The beam characteristic conditioner, in responseto a control input indicating a change between the different laserprocess operations, controllably modifies the beam characteristics for acorresponding laser process operation of the different laser processoperations. The delivery fiber has an input end coupled to the beamcharacteristic conditioner and an output end coupled to a process headfor performing the corresponding laser process operation.

In some embodiments, the beam characteristic conditioner has first andsecond lengths of fiber. The first length, through which the opticalbeam propagates, has a first refractive index profile (RIP). The firstRIP enables, in response to an applied perturbation, modification of thebeam characteristics to form an adjusted optical beam having modifiedbeam characteristics. The second length of fiber is coupled to the firstlength of fiber and has multiple confinement regions defining a secondRIP that is different from the first RIP. The multiple confinementregions are arranged to confine at least a portion of the adjustedoptical beam and generate from it, at an output of the second length offiber, an adjustable spatial or angular distribution that, in responseto the applied perturbation, changes for facilitating the correspondinglaser process operation.

Some advantages of using a beam characteristic conditioner overfree-space optics are simplification of the process head; reduction insize and weight of the process head; ease of use, installation, andmaintenance (e.g., no free-space optics to keep clean); beamcharacteristics are consistent along an entire propagation path definedby the feed fiber; and alignment issues between of the free-space opticsof the process head are avoided. Additional aspects and advantages willbe apparent from the following detailed description of preferredembodiments, which proceeds with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, wherein like reference numerals representlike elements, are incorporated in and constitute a part of thisspecification and, together with the description, explain the advantagesand principles of the presently disclosed technology. In the drawings,

FIG. 1 illustrates an example fiber structure for providing a laser beamhaving variable beam characteristics;

FIG. 2 depicts a cross-sectional view of an example fiber structure fordelivering a beam with variable beam characteristics;

FIG. 3 illustrates an example method of perturbing a fiber structure forproviding a beam having variable beam characteristics;

FIG. 4 is a graph illustrating the calculated spatial profile of thelowest-order mode (LP₀₁) for a first length of a fiber for differentfiber bend radii;

FIG. 5 illustrates an example of a two-dimensional intensitydistribution at a junction when a fiber for varying beam characteristicsis nearly straight;

FIG. 6 illustrates an example of a two-dimensional intensitydistribution at a junction when a fiber for varying beam characteristicsis bent with a radius chosen to preferentially excite a particularconfinement region of a second length of fiber;

FIGS. 7-10 depict experimental results to illustrate further outputbeams for various bend radii of a fiber for varying beam characteristicsshown in FIG. 2;

FIGS. 11-16 illustrate cross-sectional views of example first lengths offiber for enabling adjustment of beam characteristics in a fiberassembly;

FIGS. 17-19 illustrate cross-sectional views of example second lengthsof fiber (“confinement fibers”) for confining adjusted beamcharacteristics in a fiber assembly;

FIGS. 20 and 21 illustrate cross-sectional views of example secondlengths of fiber for changing a divergence angle of and confining anadjusted beam in a fiber assembly configured to provide variable beamcharacteristics;

FIG. 22A illustrates an example laser system including a fiber assemblyconfigured to provide variable beam characteristics disposed between afeeding fiber and process head;

FIG. 22B illustrates an example a laser system including a fiberassembly configured to provide variable beam characteristics disposedbetween a feeding fiber and process head;

FIG. 23 illustrates an example laser system including a fiber assemblyconfigured to provide variable beam characteristics disposed between afeeding fiber and multiple process fibers;

FIG. 24 illustrates examples of various perturbation assemblies forproviding variable beam characteristics according to various examplesprovided herein;

FIG. 25 illustrates an example process for adjusting and maintainingmodified characteristics of an optical beam;

FIGS. 26-28 are cross-sectional views illustrating example secondlengths of fiber (“confinement fibers”) for confining adjusted beamcharacteristics in a fiber assembly;

FIG. 29 is a block diagram of a multi-operation optical beam deliverydevice, according to one embodiment;

FIG. 30 is a block diagram of a multi-operation optical beam deliverydevice, according to another embodiment showing a supplemental optionalzoom optic and a series of three single-purpose nozzles;

FIG. 31 is a cross-sectional view, taken along lines 31-31 of FIG. 29,showing a multi-operation nozzle, according to one embodiment;

FIG. 32 is a sectional view, taken along lines 32-32 of FIG. 29, showingthe multi-operation nozzle; and

FIG. 33 is a bottom plan view of a multi-operation nozzle, according toanother embodiment.

DETAILED DESCRIPTION

As used herein throughout this disclosure and in the claims, thesingular forms “a,” “an,” and “the” include the plural forms unless thecontext clearly dictates otherwise. Additionally, the term “includes”means “comprises.” Further, the term “coupled” does not exclude thepresence of intermediate elements between the coupled items. Also, theterms “modify” and “adjust” are used interchangeably to mean “alter.”

The systems, apparatus, and methods described herein should not beconstrued as limiting in any way. Instead, the present disclosure isdirected toward all novel and non-obvious features and aspects of thevarious disclosed embodiments, alone and in various combinations andsub-combinations with one another. The disclosed systems, methods, andapparatus are not limited to any specific aspect or feature orcombinations thereof, nor do the disclosed systems, methods, andapparatus require that any one or more specific advantages be present orproblems be solved. Any theories of operation are to facilitateexplanation, but the disclosed systems, methods, and apparatus are notlimited to such theories of operation.

Although the operations of some of the disclosed methods are describedin a particular sequential order for convenient presentation, it shouldbe understood that this manner of description encompasses rearrangement,unless a particular ordering is required by specific language set forthbelow. For example, operations described sequentially may in some casesbe rearranged or performed concurrently. Moreover, for the sake ofsimplicity, the attached figures may not show the various ways in whichthe disclosed systems, methods, and apparatus can be used in conjunctionwith other systems, methods, and apparatus. Additionally, thedescription sometimes uses terms like “produce” and “provide” todescribe the disclosed methods. These terms are high-level abstractionsof the actual operations that are performed. The actual operations thatcorrespond to these terms will vary depending on the particularimplementation and are readily discernible by one of ordinary skill inthe art.

In some examples, values, procedures, or apparatus are referred to as“lowest,” “best,” “minimum,” or the like. It will be appreciated thatsuch descriptions are intended to indicate that a selection among manyused functional alternatives can be made, and such selections need notbe better, smaller, or otherwise preferable to other selections.Examples are described with reference to directions indicated as“above,” “below,” “upper,” “lower,” and the like. These terms are usedfor convenient description, but do not imply any particular spatialorientation.

Definitions

Definitions of words and terms as used herein:

-   1. The term “beam characteristics” refers to one or more of the    following terms used to describe an optical beam. In general, the    beam characteristics of most interest depend on the specifics of the    application or optical system.-   2. The term “beam diameter” is defined as the distance across the    center of the beam along an axis for which the irradiance    (intensity) equals 1/e² of the maximum irradiance. While examples    disclosed herein generally use beams that propagate in azimuthally    symmetric modes, elliptical or other beam shapes can be used, and    beam diameter can be different along different axes. Circular beams    are characterized by a single beam diameter. Other beam shapes can    have different beam diameters along different axes.-   3. The term “spot size” is the radial distance (radius) from the    center point of maximum irradiance to the 1/e² point.-   4. The term “beam divergence distribution” is the power vs the full    cone angle. This quantity is sometimes called the “angular    distribution” or “NA distribution.”-   5. The term “beam parameter product” (BPP) of a laser beam is    defined as the product of the beam radius (measured at the beam    waist) and the beam divergence half-angle (measured in the far    field). The units of BPP are typically mm-mrad.-   6. A “confinement fiber” is defined to be a fiber that possesses one    or more confinement regions, wherein a confinement region comprises    a higher-index region (core region) surrounded by a lower-index    region (cladding region). The RIP of a confinement fiber may include    one or more higher-index regions (core regions) surrounded by    lower-index regions (cladding regions), wherein light is guided in    the higher-index regions. Each confinement region and each cladding    region can have any RIP, including but not limited to step-index and    graded-index. The confinement regions may or may not be concentric    and may be a variety of shapes such as circular, annular, polygonal,    arcuate, elliptical, or irregular, or the like or any combination    thereof. The confinement regions in a particular confinement fiber    may all have the same shape or may be different shapes. Moreover,    confinement regions may be co-axial or may have offset axes with    respect to one another. Confinement regions may be of uniform    thickness about a central axis in the longitudinal direction, or the    thicknesses may vary about the central axis in the longitudinal    direction.-   7. The term “intensity distribution” refers to optical intensity as    a function of position along a line (1D profile) or on a plane (2D    profile). The line or plane is usually taken perpendicular to the    propagation direction of the light. It is a quantitative property.-   8. “Luminance” is a photometric measure of the luminous intensity    per unit area of light travelling in a given direction.-   9. “M² factor” (also called “beam quality factor” or “beam    propagation factor”) is a dimensionless parameter for quantifying    the beam quality of laser beams, with M²=1 being a    diffraction-limited beam, and larger M² values corresponding to    lower beam quality. M² is equal to the BPP divided by λ/π, where λ    is the wavelength of the beam in microns (if BPP is expressed in    units of mm-mrad).-   10. The term “numerical aperture” or “NA” of an optical system is a    dimensionless number that characterizes the range of angles over    which the system can accept or emit light.-   11. The term “optical intensity” is not an official (SI) unit, but    is used to denote incident power per unit area on a surface or    passing through a plane.-   12. The term “power density” refers to optical power per unit area,    although this is also referred to as “optical intensity.”-   13. The term “radial beam position” refers to the position of a beam    in a fiber measured with respect to the center of the fiber core in    a direction perpendicular to the fiber axis.-   14. “Radiance” is the radiation emitted per unit solid angle in a    given direction by a unit area of an optical source (e.g., a laser).    Radiance may be altered by changing the beam intensity distribution    and/or beam divergence profile or distribution. The ability to vary    the radiance profile of a laser beam implies the ability to vary the    BPP.-   15. The term “refractive-index profile” or “RIP” refers to the    refractive index as a function of position along a line (1D) or in a    plane (2D) perpendicular to the fiber axis. Many fibers are    azimuthally symmetric, in which case the 1D RIP is identical for any    azimuthal angle.-   16. A “step-index fiber” has a RIP that is flat (refractive index    independent of position) within the fiber core.-   17. A “graded-index fiber” has a RIP in which the refractive index    decreases with increasing radial position (i.e., with increasing    distance from the center of the fiber core).-   18. A “parabolic-index fiber” is a specific case of a graded-index    fiber in which the refractive index decreases quadratically with    increasing distance from the center of the fiber core.    Fiber for Varying Beam Characteristics

Disclosed herein are methods, systems, and apparatus configured toprovide a fiber operable to provide a laser beam having variable beamcharacteristics (VBC) that may reduce cost, complexity, optical loss, orother drawbacks of the conventional methods described above. This VBCfiber is configured to vary a wide variety of optical beamcharacteristics. Such beam characteristics can be controlled using theVBC fiber thus allowing users to tune various beam characteristics tosuit the particular requirements of an extensive variety of laserprocessing applications. For example, a VBC fiber may be used to tunebeam diameter, beam divergence distribution, BPP, intensitydistribution, M² factor, NA, optical intensity, power density, radialbeam position, radiance, spot size, or the like, or any combinationthereof.

In general, the disclosed technology entails coupling a laser beam intoa fiber in which the characteristics of the laser beam in the fiber canbe adjusted by perturbing the laser beam and/or perturbing a firstlength of fiber by any of a variety of methods (e.g., bending the fiberor introducing one or more other perturbations) and fully or partiallymaintaining adjusted beam characteristics in a second length of fiber.The second length of fiber is specially configured to maintain and/orfurther modify the adjusted beam characteristics. In some cases, thesecond length of fiber preserves the adjusted beam characteristicsthrough delivery of the laser beam to its ultimate use (e.g., materialsprocessing). The first and second lengths of fiber may comprise the sameor different fibers.

The disclosed technology is compatible with fiber lasers andfiber-coupled lasers. Fiber-coupled lasers typically deliver an outputvia a delivery fiber having a step-index refractive index profile (RIP),i.e., a flat or constant refractive index within the fiber core. Inreality, the RIP of the delivery fiber may not be perfectly flat,depending on the design of the fiber. Important parameters are the fibercore diameter (d_(core)) and NA. The core diameter is typically in therange of 10-1000 microns (although other values are possible), and theNA is typically in the range of 0.06-0.22 (although other values arepossible). A delivery fiber from the laser may be routed directly to theprocess head or workpiece, or it may be routed to a fiber-to-fibercoupler (FFC) or fiber-to-fiber switch (FFS), which couples the lightfrom the delivery fiber into a process fiber that transmits the beam tothe process head or the workpiece.

Most materials processing tools, especially those at high power (>1 kW),employ multimode (MM) fiber, but some employ single-mode (SM) fiber,which is at the lower end of the d_(core) and NA ranges. The beamcharacteristics from a SM fiber are uniquely determined by the fiberparameters. The beam characteristics from a MM fiber, however, can vary(unit-to-unit and/or as a function of laser power and time), dependingon the beam characteristics from the laser source(s) coupled into thefiber, the launching or splicing conditions into the fiber, the fiberRIP, and the static and dynamic geometry of the fiber (bending, coiling,motion, micro-bending, etc.). For both SM and MM delivery fibers, thebeam characteristics may not be optimum for a given materials processingtask, and it is unlikely to be optimum for a range of tasks, motivatingthe desire to be able to systematically vary the beam characteristics inorder to customize or optimize them for a particular processing task.

In one example, the VBC fiber may have a first length and a secondlength and may be configured to be interposed as an in-fiber devicebetween the delivery fiber and the process head to provide the desiredadjustability of the beam characteristics. To enable adjustment of thebeam, a perturbation device and/or assembly is disposed in closeproximity to and/or coupled with the VBC fiber and is responsible forperturbing the beam in a first length such that the beam'scharacteristics are altered in the first length of fiber, and thealtered characteristics are preserved or further altered as the beampropagates in the second length of fiber. The perturbed beam is launchedinto a second length of the VBC fiber configured to conserve adjustedbeam characteristics. The first and second lengths of fiber may be thesame or different fibers and/or the second length of fiber may comprisea confinement fiber. The beam characteristics that are conserved by thesecond length of VBC fiber may include any of: beam diameter, beamdivergence distribution, BPP, intensity distribution, luminance, M²factor, NA, optical intensity, power density, radial beam position,radiance, spot size, or the like, or any combination thereof.

FIG. 1 illustrates an example VBC fiber 100 for providing a laser beamhaving variable beam characteristics without requiring the use offree-space optics to change the beam characteristics. VBC fiber 100comprises a first length of fiber 104 and a second length of fiber 108.First length of fiber 104 and second length of fiber 108 may be the sameor different fibers and may have the same or different RIPs. The firstlength of fiber 104 and the second length of fiber 108 may be joinedtogether by a splice. First length of fiber 104 and second length offiber 108 may be coupled in other ways, may be spaced apart, or may beconnected via an interposing component such as another length of fiber,free-space optics, glue, index-matching material, or the like or anycombination thereof.

A perturbation device 110 is disposed proximal to and/or envelops aperturbation region 106. Perturbation device 110 may be a device,assembly, in-fiber structure, and/or other feature. Perturbation device110 at least perturbs optical beam 102 in first length of fiber 104 orsecond length of fiber 108 or a combination thereof in order to adjustone or more beam characteristics of optical beam 102. Adjustment of beam102 responsive to perturbation by perturbation device 110 may occur infirst length of fiber 104 or second length of fiber 108 or a combinationthereof. Perturbation region 106 may extend over various widths and mayor may not extend into a portion of second length of fiber 108. As beam102 propagates in VBC fiber 100, perturbation device 110 may physicallyact on VBC fiber 100 to perturb the fiber and adjust the characteristicsof beam 102. Alternatively, perturbation device 110 may act directly onbeam 102 to alter its beam characteristics. Subsequent to beingadjusted, perturbed beam 112 has different beam characteristics fromthose of beam 102, which will be fully or partially conserved in secondlength of fiber 108. In another example, perturbation device 110 neednot be disposed near a splice. Moreover, a splice may not be needed atall, for example VBC fiber 100 may be a single fiber, first length offiber and second length of fiber could be spaced apart, or secured witha small gap (air-spaced or filled with an optical material, such asoptical cement or an index-matching material).

Perturbed beam 112 is launched into second length of fiber 108, whereperturbed beam 112 characteristics are largely maintained or continue toevolve as perturbed beam 112 propagates yielding the adjusted beamcharacteristics at the output of second length of fiber 108. In oneexample, the new beam characteristics may include an adjusted intensitydistribution. In an example, an altered beam intensity distribution willbe conserved in various structurally bounded confinement regions ofsecond length of fiber 108. Thus, the beam intensity distribution may betuned to a desired beam intensity distribution optimized for aparticular laser processing task. In general, the intensity distributionof perturbed beam 112 will evolve as it propagates in the second lengthof fiber 108 to fill the confinement region(s) into which perturbed beam112 is launched responsive to conditions in first length of fiber 104and perturbation caused by perturbation device 110. In addition, theangular distribution may evolve as the beam propagates in the secondfiber, depending on launch conditions and fiber characteristics. Ingeneral, fibers largely preserve the input divergence distribution, butthe distribution can be broadened if the input divergence distributionis narrow and/or if the fiber has irregularities or deliberate featuresthat perturb the divergence distribution. The various confinementregions, perturbations, and fiber features of second length of fiber 108are described in greater detail below. Beams 102 and 112 are conceptualabstractions intended to illustrate how a beam may propagate through aVBC fiber 100 for providing variable beam characteristics and are notintended to closely model the behavior of a particular optical beam.

VBC fiber 100 may be manufactured by a variety of methods including PCVD(Plasma Chemical Vapor Deposition), OVD (Outside Vapor Deposition), VAD(Vapor Axial Deposition), MOCVD (Metal-Organic Chemical VaporDeposition.) and/or DND (Direct Nanoparticle Deposition). VBC fiber 100may comprise a variety of materials. For example, VBC fiber 100 maycomprise SiO₂, SiO₂ doped with GeO₂, germanosilicate, phosphoruspentoxide, phosphosilicate, Al₂O₃, aluminosilicate, or the like or anycombinations thereof. Confinement regions may be bounded by claddingdoped with fluorine, boron, or the like or any combinations thereof.Other dopants may be added to active fibers, including rare-earth ionssuch as Er³⁺ (erbium), Yb³⁺ (ytterbium), Nd³⁺ (neodymium), Tm³⁺(thulium), Ho³⁺ (holmium), or the like or any combination thereof.Confinement regions may be bounded by cladding having a lower index thanthat of the confinement region with fluorine or boron doping.Alternatively, VBC fiber 100 may comprise photonic crystal fibers ormicro-structured fibers.

VBC fiber 100 is suitable for use in any of a variety of fiber, fiberoptic, or fiber laser devices, including continuous wave and pulsedfiber lasers, disk lasers, solid state lasers, or diode lasers (pulserate unlimited except by physical constraints). Furthermore,implementations in a planar waveguide or other types of waveguides andnot just fibers are within the scope of the claimed technology.

FIG. 2 depicts a cross-sectional view of an example VBC fiber 200 foradjusting beam characteristics of an optical beam. In an example, VBCfiber 200 may be a process fiber because it may deliver the beam to aprocess head for material processing. VBC fiber 200 comprises a firstlength of fiber 204 spliced at a junction 206 to a second length offiber 208. A perturbation assembly 210 is disposed proximal to junction206. Perturbation assembly 210 may be any of a variety of devicesconfigured to enable adjustment of the beam characteristics of anoptical beam 202 propagating in VBC fiber 200. In an example,perturbation assembly 210 may be a mandrel and/or another device thatmay provide means of varying the bend radius and/or bend length of VBCfiber 200 near the splice. Other examples of perturbation devices arediscussed below with respect to FIG. 24.

In an example, first length of fiber 204 has a parabolic-index RIP 212as indicated by the left RIP graph. Most of the intensity distributionof beam 202 is concentrated in the center of fiber 204 when fiber 204 isstraight or nearly straight. Second length of fiber 208 is a confinementfiber having RIP 214 as shown in the right RIP graph. Second length offiber 208 includes confinement regions 216, 218, and 220. Confinementregion 216 is a central core surrounded by two annular (or ring-shaped)confinement regions 218 and 220. Layers 222 and 224 are structuralbarriers of lower index material between confinement regions (216, 218and 220), commonly referred to as “cladding” regions. In one example,layers 222 and 224 may comprise rings of fluorosilicate; in someembodiments, the fluorosilicate cladding layers are relatively thin.Other materials may be used as well, and claimed subject matter is notlimited in this regard.

In an example, as beam 202 propagates along VBC fiber 200, perturbationassembly 210 may physically act on fiber 204 and/or beam 202 to adjustits beam characteristics and generate an adjusted beam 226. In thecurrent example, the intensity distribution of beam 202 is modified byperturbation assembly 210. Subsequent to adjustment of beam 202, theintensity distribution of adjusted beam 226 may be concentrated in outerconfinement regions 218 and 220 with relatively little intensity in thecentral confinement region 216. Because each of confinement regions 216,218, and/or 220 is isolated by the thin layers of lower index materialin barrier layers 222 and 224, second length of fiber 208 cansubstantially maintain the adjusted intensity distribution of adjustedbeam 226. The beam will typically become distributed azimuthally withina given confinement region but will not transition (significantly)between the confinement regions as it propagates along the second lengthof fiber 208. Thus, the adjusted beam characteristics of adjusted beam226 are largely conserved within the isolated confinement regions 216,218, and/or 220. In some cases, it be may desirable to have the beam 226power divided among the confinement regions 216, 218, and/or 220 ratherthan concentrated in a single region, and this condition may be achievedby generating an appropriately adjusted beam 226.

In one example, core confinement region 216 and annular confinementregions 218 and 220 may be composed of fused silica glass, and cladding222 and 224 defining the confinement regions may be composed offluorosilicate glass. Other materials may be used to form the variousconfinement regions (216, 218 and 220), including germanosilicate,phosphosilicate, aluminosilicate, or the like, or a combination thereofand claimed subject matter is not so limited. Other materials may beused to form the barrier rings (222 and 224), including fused silica,borosilicate, or the like or a combination thereof, and claimed subjectmatter is not so limited. In other embodiments, the optical fibers orwaveguides include or are composed of various polymers or plastics orcrystalline materials. Generally, the core confinement regions haverefractive indices that are greater than the refractive indices ofadjacent barrier/cladding regions.

In some examples, it may be desirable to increase a number ofconfinement regions in a second length of fiber to increase granularityof beam control over beam displacements for fine-tuning a beam profile.For example, confinement regions may be configured to provide stepwisebeam displacement.

FIG. 3 illustrates an example method of perturbing fiber 200 forproviding variable beam characteristics of an optical beam. Changing thebend radius of a fiber may change the radial beam position, divergenceangle, and/or radiance profile of a beam within the fiber. The bendradius of VBC fiber 200 can be decreased from a first bend radius R₁ toa second bend radius R₂ about splice junction 206 by using a steppedmandrel or cone as the perturbation assembly 210. Additionally oralternatively, the engagement length on the mandrel(s) or cone can bevaried. Rollers 250 may be employed to engage VBC fiber 200 acrossperturbation assembly 210. In an example, an amount of engagement ofrollers 250 with fiber 200 has been shown to shift the distribution ofthe intensity profile to the outer confinement regions 218 and 220 offiber 200 with a fixed mandrel radius. There are a variety of othermethods for varying the bend radius of fiber 200, such as using aclamping assembly, flexible tubing, or the like, or a combinationthereof, and claimed subject matter is not limited in this regard. Inanother example, for a particular bend radius the length over which VBCfiber 200 is bent can also vary beam characteristics in a controlled andreproducible way. In examples, changing the bend radius and/or lengthover which the fiber is bent at a particular bend radius also modifiesthe intensity distribution of the beam such that one or more modes maybe shifted radially away from the center of a fiber core.

Maintaining the bend radius of the fibers across junction 206 ensuresthat the adjusted beam characteristics such as radial beam position andradiance profile of optical beam 202 will not return to its unperturbedstate before being launched into second length of fiber 208. Moreover,the adjusted radial beam characteristics, including position, divergenceangle, and/or intensity distribution, of adjusted beam 226 can be variedbased on an extent of decrease in the bend radius and/or the extent ofthe bent length of VBC fiber 200. Thus, specific beam characteristicsmay be obtained using this method.

In the current example, first length of fiber 204 having first RIP 212is spliced at junction 206 to a second length of fiber 208 having asecond RIP 214. However, it is possible to use a single fiber having asingle RIP formed to enable perturbation (e.g., by micro-bending) of thebeam characteristics of beam 202 and to enable conservation of theadjusted beam. Such a RIP may be similar to the RIPs shown in fibersillustrated in FIGS. 17, 18, and/or 19.

FIGS. 7-10 provide experimental results for VBC fiber 200 (shown inFIGS. 2 and 3) and illustrate further a beam response to perturbation ofVBC fiber 200 when a perturbation assembly 210 acts on VBC fiber 200 tobend the fiber. FIGS. 4-6 are simulations and FIGS. 7-10 areexperimental results wherein a beam from a SM 1050 nm source waslaunched into an input fiber (not shown) with a 40 micron core diameter.The input fiber was spliced to first length of fiber 204.

FIG. 4 is an example graph 400 illustrating the calculated profile ofthe lowest-order mode (LP₀₁) for a first length of fiber 204 fordifferent fiber bend radii 402, wherein a perturbation assembly 210involves bending VBC fiber 200. As the fiber bend radius is decreased,an optical beam propagating in VBC fiber 200 is adjusted such that themode shifts radially away from the center 404 of a VBC fiber 200 core(r=0 micron) toward the core/cladding interface (located at r=100 micronin this example). Higher-order modes (LP_(In)) also shift with bending.Thus, for a straight or nearly straight fiber (very large bend radius),curve 406 for LP₀₁ is centered at or near the center of VBC fiber 200.At a bend radius of about 6 cm, curve 408 for LP₀₁ is shifted to aradial position of about 40 μm from the center 406 of VBC fiber 200. Ata bend radius of about 5 cm, curve 410 for LP₀₁ is shifted to a radialposition about 50 μm from the center 406 of VBC fiber 200. At a bendradius of about 4 cm, curve 412 for LP₀₁ is shifted to a radial positionabout 60 μm from the center 406 of VBC fiber 200. At a bend radius ofabout 3 cm, curve 414 for LP₀₁ is shifted to a radial position about 80μm from the center 406 of VBC fiber 200. At a bend radius of about 2.5cm, a curve 416 for LP₀₁ is shifted to a radial position about 85 μmfrom the center 406 of VBC fiber 200. Note that the shape of the moderemains relatively constant (until it approaches the edge of the core),which is a specific property of a parabolic RIP. Although, this propertymay be desirable in some situations, it is not required for the VBCfunctionality, and other RIPs may be employed.

In an example, if VBC fiber 200 is straightened, LP₀₁ mode will shiftback toward the center of the fiber. Thus, the purpose of second lengthof fiber 208 is to “trap” or confine the adjusted intensity distributionof the beam in a confinement region that is displaced from the center ofthe VBC fiber 200. The splice between fibers 204 and 208 is included inthe bent region, thus the shifted mode profile will be preferentiallylaunched into one of the ring-shaped confinement regions 218 and 220 orbe distributed among the confinement regions. FIGS. 5 and 6 illustratethis effect.

FIG. 5 illustrates an example of two-dimensional intensity distributionat junction 206 within second length of fiber 208 when VBC fiber 200 isnearly straight. A significant portion of LP₀₁ and LP_(In) is withinconfinement region 216 of fiber 208. FIG. 6 illustrates thetwo-dimensional intensity distribution at junction 206 within secondlength of fiber 208 when VBC fiber 200 is bent with a radius chosen topreferentially excite confinement region 220 (the outermost confinementregion) of second length of fiber 208. A significant portion of LP₀₁ andLP_(In) is within confinement region 220 of fiber 208.

In an example, in second length of fiber 208, confinement region 216 hasa 100 micron diameter, confinement region 218 is between 120 micron and200 micron in diameter, and confinement region 220 is between 220 micronand 300 micron diameter. Confinement regions 216, 218, and 220 areseparated by 10 μm thick rings of fluorosilicate, providing an NA of0.22 for the confinement regions. Other inner and outer diameters forthe confinement regions, thicknesses of the rings separating theconfinement regions, NA values for the confinement regions, and numbersof confinement regions may be employed.

Referring again to FIG. 5, with the noted parameters, when VBC fiber 200is straight, about 90% of the power is contained within the centralconfinement region 216, and about 100% of the power is contained withinconfinement regions 216 and 218. Referring now to FIG. 6, when fiber 200is bent to preferentially excite second ring confinement region 220,nearly 75% of the power is contained within confinement region 220, andmore than 95% of the power is contained within confinement regions 218and 220. These calculations include LP₀₁ and two higher-order modes,which are typical in some 2-4 kW fiber lasers.

It is clear from FIGS. 5 and 6 that, in the case where a perturbationassembly 210 acts on VBC fiber 200 to bend the fiber, the bend radiusdetermines the spatial overlap of the modal intensity distribution ofthe first length of fiber 204 with the different guiding confinementregions (216, 218, and 220) of the second length of fiber 208. Changingthe bend radius can thus change the intensity distribution at the outputof the second length of fiber 208, thereby changing the diameter or spotsize of the beam, and thus changing its radiance and BPP value. Thisadjustment of the spot size may be accomplished in an all-fiberstructure, involving no free-space optics and consequently may reduce oreliminate the disadvantages of free-space optics discussed above. Suchadjustments can also be made with other perturbation assemblies thatalter bend radius, bend length, fiber tension, temperature, or otherperturbations discussed below.

In a typical materials processing system (e.g., a cutting or weldingtool), the output of the process fiber is imaged at or near theworkpiece by the process head. Varying the intensity distribution asshown in FIGS. 5 and 6 thus enables variation of the beam profile at theworkpiece in order to tune and/or optimize the process, as desired.Specific RIPs for the two fibers were assumed for the purpose of theabove calculations, but other RIPs are possible, and claimed subjectmatter is not limited in this regard.

FIGS. 7-10 depict experimental results (measured intensitydistributions) to illustrate further output beams for various bend radiiof VBC fiber 200 shown in FIG. 2.

In FIG. 7 when VBC fiber 200 is straight, the beam is nearly completelyconfined to confinement region 216. As the bend radius is decreased, theintensity distribution at the output shifts to the larger diameters ofconfinement regions 218 and 220 located farther away from confinementregion 216—see e.g., this shift visible in FIGS. 8-10. FIG. 8 depictsthe intensity distribution when the bend radius of VBC fiber 200 ischosen to shift the intensity distribution preferentially to confinementregion 218. FIG. 9 depicts the experimental results when the bend radiusis further reduced and chosen to shift the intensity distributionoutward to confinement region 220 and confinement region 218. In FIG.10, at the smallest bend radius, the beam is nearly a “donut mode,” withmost of the intensity in the outermost confinement region 220.

Despite excitation of the confinement regions from one side at thesplice junction 206, the intensity distributions are nearly symmetricazimuthally because of scrambling within confinement regions as the beampropagates within the VBC fiber 200. Although the beam will typicallyscramble azimuthally as it propagates, various structures orperturbations (e.g., coils) could be included to facilitate thisprocess.

For the fiber parameters used in the experiment shown in FIGS. 7-10,particular confinement regions were not exclusively excited because someintensity was present in multiple confinement regions. This feature mayenable advantageous materials processing applications that are optimizedby having a flatter or distributed beam intensity distribution. Inapplications requiring cleaner excitation of a given confinement region,different fiber RIPs could be employed to enable this feature.

The results shown in FIGS. 7-10 pertain to the particular fibers used inthis experiment, and the details will vary depending on the specifics ofthe implementation. In particular, the spatial profile and divergencedistribution of the output beam and their dependence on bend radius willdepend on the specific RIPs employed, on the splice parameters, and onthe characteristics of the laser source launched into the first fiber.

Different fiber parameters from those shown in FIG. 2 may be used andstill be within the scope of the claimed subject matter. Specifically,different RIPs and core sizes and shapes may be used to facilitatecompatibility with different input beam profiles and to enable differentoutput beam characteristics. Example RIPs for the first length of fiber,in addition to the parabolic-index profile shown in FIG. 2, includeother graded-index profiles, step-index, pedestal designs (i.e., nestedcores with progressively lower refractive indices with increasingdistance from the center of the fiber), and designs with nested coreswith the same refractive index value but with various NA values for thecentral core and the surrounding rings. Example RIPs for the secondlength of fiber, in addition to the profile shown in FIG. 2, includeconfinement fibers with different numbers of confinement regions,non-uniform confinement-region thicknesses, different and/or non-uniformvalues for the thicknesses of the rings surrounding the confinementregions, different and/or non-uniform NA values for the confinementregions, different refractive-index values for the high-index andlow-index portions of the RIP, non-circular confinement regions (such aselliptical, oval, polygonal, square, rectangular, or combinationsthereof), as well as other designs as discussed in further detail withrespect to FIGS. 26-28. Furthermore, VBC fiber 200 and other examples ofa VBC fiber described herein are not restricted to use of two fibers. Insome examples, implementation may include use of one fiber or more thantwo fibers. In some cases, the fiber(s) may not be axially uniform; forexample, they could include fiber Bragg gratings or long-periodgratings, or the diameter could vary along the length of the fiber. Inaddition, the fibers do not have to be azimuthally symmetric, e.g., thecore(s) could have square or polygonal shapes. Various fiber coatings(buffers) may be employed, including high-index or index-matchedcoatings (which strip light at the glass-polymer interface) andlow-index coatings (which guide light by total internal reflection atthe glass-polymer interface). In some examples, multiple fiber coatingsmay be used on VBC fiber 200.

FIGS. 11-16 illustrate cross-sectional views of examples of firstlengths of fiber for enabling adjustment of beam characteristics in aVBC fiber responsive to perturbation of an optical beam propagating inthe first lengths of fiber. Some examples of beam characteristics thatmay be adjusted in the first length of fiber are: beam diameter, beamdivergence distribution, BPP, intensity distribution, luminance, M²factor, NA, optical intensity profile, power density profile, radialbeam position, radiance, spot size, or the like, or any combinationthereof. The first lengths of fiber depicted in FIGS. 11-16 anddescribed below are merely examples and do not provide an exhaustiverecitation of the variety of first lengths of fiber that may be utilizedto enable adjustment of beam characteristics in a VBC fiber assembly.Selection of materials, appropriate RIPs, and other variables for thefirst lengths of fiber illustrated in FIGS. 11-16 at least depend on adesired beam output. A wide variety of fiber variables are contemplatedand are within the scope of the claimed subject matter. Thus, claimedsubject matter is not limited by examples provided herein.

In FIG. 11 first length of fiber 1100 comprises a step-index profile1102. FIG. 12 illustrates a first length of fiber 1200 comprising a“pedestal RIP” (i.e., a core comprising a step-index region surroundedby a larger step-index region) 1202. FIG. 13 illustrates a first lengthof fiber 1300 comprising a multiple-pedestal RIP 1302.

FIG. 14A illustrates a first length of fiber 1400 comprising agraded-index profile 1418 surrounded by a down-doped region 1404. Whenthe fiber 1400 is perturbed, modes may shift radially outward in fiber1400 (e.g., during bending of fiber 1400). Graded-index profile 1402 maybe designed to promote maintenance or even compression of modal shape.This design may promote adjustment of a beam propagating in fiber 1400to generate a beam having a beam intensity distribution concentrated inan outer perimeter of the fiber (i.e., in a portion of the fiber corethat is displaced from the fiber axis). As described above, when theadjusted beam is coupled into a second length of fiber havingconfinement regions, the intensity distribution of the adjusted beam maybe trapped in the outermost confinement region, providing a donut shapedintensity distribution. A beam spot having a narrow outer confinementregion may be useful to enable certain material processing actions.

FIG. 14B illustrates a first length of fiber 1406 comprising agraded-index profile 1414 surrounded by a down-doped region 1408 similarto that of fiber 1400. However, fiber 1406 includes a divergencestructure 1410 (a lower-index region) as can be seen in profile 1412.The divergence structure 1410 is an area of material with a lowerrefractive index than that of the surrounding core. As the beam islaunched into first length of fiber 1406, refraction from divergencestructure 1410 causes the beam divergence to increase in first length offiber 1406. The amount of increased divergence depends on the amount ofspatial overlap of the beam with the divergence structure 1410 and themagnitude of the index difference between the divergence structure 1410and the core material. Divergence structure 1410 can have a variety ofshapes, depending on the input divergence distribution and desiredoutput divergence distribution. In an example, divergence structure 1410has a triangular or graded index shape.

FIG. 15 illustrates a first length of fiber 1500 comprising aparabolic-index central region 1502 surrounded by a constant-indexregion 1504. Between the constant-index region 1504 and theparabolic-index central region 1502 is a lower-index annular layer (orlower-index ring or annulus) 1506 surrounding the parabolic-indexcentral region 1502. The lower-index annulus 1506 helps guide a beampropagating in fiber 1500. When the propagating beam is perturbed, modesshift radially outward in fiber 1500 (e.g., during bending of fiber1500). As one or more modes shift radially outward, parabolic-indexregion 1502 promotes retention of modal shape. When the modes reach theconstant-index region 1504 at outer portions of a RIP 1510, they will becompressed against the lower-index ring 1506, which (in comparison tothe first fiber RIP shown in FIGS. 14A and 14B) may cause preferentialexcitation of the outermost confinement region in the second fiber. Inone implementation, this fiber design works with a confinement fiberhaving a central step-index core and a single annular core. Theparabolic-index portion 1502 of the RIP 1510 overlaps with the centralstep-index core of the confinement fiber. The constant-index portion1504 overlaps with the annular core of the confinement fiber. Theconstant-index portion 1504 of the first fiber is intended to make iteasier to move the beam into overlap with the annular core by bending.This fiber design also works with other designs of the confinementfiber.

FIG. 16 illustrates a first length of fiber 1600 comprising guidingregions 1604, 1606, 1608, and 1616 bounded by lower-index layers 1610,1612, and 1614 where the indexes of the lower-index layers 1610, 1612,and 1614 are stepped or, more generally, do not all have the same value.The stepped-index layers may serve to bound the beam intensity tocertain guiding regions (1604, 1606, 1608, and 1616) when theperturbation assembly 210 (see FIG. 2) acts on the fiber 1600. In thisway, adjusted beam light may be trapped in the guiding regions over arange of perturbation actions (such as over a range of bend radii, arange of bend lengths, a range of micro-bending pressures, and/or arange of acousto-optical signals), allowing for a certain degree ofperturbation tolerance before a beam intensity distribution is shiftedto a more distant radial position in fiber 1600. Thus, variation in beamcharacteristics may be controlled in a step-wise fashion. The radialwidths of the guiding regions 1604, 1606, 1608, and 1616 may be adjustedto achieve a desired ring width, as may be required by an application.Also, a guiding region can have a thicker radial width to facilitatetrapping of a larger fraction of the incoming beam profile if desired.Region 1606 is an example of such a design.

FIGS. 17-21 depict examples of fibers configured to enable maintenanceand/or confinement of adjusted beam characteristics in the second lengthof fiber (e.g., fiber 208). These fiber designs are referred to as“ring-shaped confinement fibers” because they contain a central coresurrounded by annular or ring-shaped cores. These designs are merelyexamples and not an exhaustive recitation of the variety of fiber RIPsthat may be used to enable maintenance and/or confinement of adjustedbeam characteristics within a fiber. Thus, claimed subject matter is notlimited to the examples provided herein. Moreover, any of the firstlengths of fiber described above with respect to FIGS. 11-16 may becombined with any of the second length of fiber described FIGS. 17-21.

FIG. 17 illustrates a cross-sectional view of an example second lengthof fiber for maintaining and/or confining adjusted beam characteristicsin a VBC fiber assembly. As the perturbed beam is coupled from a firstlength of fiber to a second length of fiber 1700, the second length offiber 1700 may maintain at least a portion of the beam characteristicsadjusted in response to perturbation in the first length of fiber withinone or more of confinement regions 1704, 1706, and/or 1708. Fiber 1700has a RIP 1702. Each of confinement regions 1704, 1706, and/or 1708 isbounded by a lower index layer 1710 and/or 1712. This design enablessecond length of fiber 1700 to maintain the adjusted beamcharacteristics. As a result, a beam output by fiber 1700 willsubstantially maintain the received adjusted beam as modified in thefirst length of fiber giving the output beam adjusted beamcharacteristics, which may be customized to a processing task or otherapplication.

Similarly, FIG. 18 depicts a cross-sectional view of an example secondlength of fiber 1800 for maintaining and/or confining beamcharacteristics adjusted in response to perturbation in the first lengthof fiber in a VBC fiber assembly. Fiber 1800 has a RIP 1802. However,confinement regions 1808, 1810, and/or 1812 have different thicknessesfrom the thicknesses of confinement regions 1704, 1706, and 1708. Eachof confinement regions 1808, 1810, and/or 1812 is bounded by a lowerindex layer 1804 and/or 1806. Varying the thicknesses of the confinementregions (and/or barrier regions) enables tailoring or optimization of aconfined adjusted radiance profile by selecting particular radialpositions within which to confine an adjusted beam.

FIG. 19 depicts a cross-sectional view of an example second length offiber 1900 having a RIP 1902 for maintaining and/or confining anadjusted beam in a VBC fiber assembly configured to provide variablebeam characteristics. In this example, the number and thicknesses ofconfinement regions 1904, 1906, 1908, and 1910 are different from thoseof fiber 1700 and 1800; and the barrier layers 1912, 1914, and 1916 areof varied thicknesses as well. Furthermore, confinement regions 1904,1906, 1908, and 1910 have different indexes of refraction; and barrierlayers 1912, 1914, and 1916 have different indexes of refraction aswell. This design may further enable a more granular or optimizedtailoring of the confinement and/or maintenance of an adjusted beamradiance to particular radial locations within fiber 1900. As theperturbed beam is launched from a first length of fiber to second lengthof fiber 1900, the modified beam characteristics of the beam (having anadjusted intensity distribution, radial position, and/or divergenceangle, or the like, or a combination thereof) is confined within aspecific radius by one or more of confinement regions 1904, 1906, 1908,and/or 1910 of second length of fiber 1900.

As noted previously, the divergence angle of a beam may be conserved oradjusted and then conserved in the second length of fiber. There are avariety of methods to change the divergence angle of a beam. Thefollowing are examples of fibers configured to enable adjustment of thedivergence angle of a beam propagating from a first length of fiber to asecond length of fiber in a fiber assembly for varying beamcharacteristics. However, these are merely examples and not anexhaustive recitation of the variety of methods that may be used toenable adjustment of divergence of a beam. Thus, claimed subject matteris not limited to the examples provided herein.

FIG. 20 depicts a cross-sectional view of an example second length offiber 2000 having a RIP 2002 for modifying, maintaining, and/orconfining beam characteristics adjusted in response to perturbation inthe first length of fiber. In this example, second length of fiber 2000is similar to the previously described second lengths of fiber and formsa portion of the VBC fiber assembly for delivering variable beamcharacteristics as discussed above. There are three confinement regions2004, 2006, and 2008 and three barrier layers 2010, 2012, and 2016.Second length of fiber 2000 also has a divergence structure 2014situated within the confinement region 2006. The divergence structure2014 is an area of material with a lower refractive index than that ofthe surrounding confinement region. As the beam is launched into secondlength of fiber 2000, refraction from divergence structure 2014 causesthe beam divergence to increase in second length of fiber 2000. Theamount of increased divergence depends on the amount of spatial overlapof the beam with the divergence structure 2014 and the magnitude of theindex difference between the divergence structure 2014 and the corematerial. By adjusting the radial position of the beam near the launchpoint into the second length of fiber 2000, the divergence distributionmay be varied. The adjusted divergence of the beam is conserved in fiber2000, which is configured to deliver the adjusted beam to the processhead, another optical system (e.g., fiber-to-fiber coupler orfiber-to-fiber switch), the workpiece, or the like, or a combinationthereof. In an example, divergence structure 2014 may have an index dipof about 10⁻⁵−3×10⁻² with respect to the surrounding material. Othervalues of the index dip may be employed within the scope of thisdisclosure, and claimed subject matter is not so limited.

FIG. 21 depicts a cross-sectional view of an example second length offiber 2100 having a RIP 2102 for modifying, maintaining, and/orconfining beam characteristics adjusted in response to perturbation inthe first length of fiber. Second length of fiber 2100 forms a portionof a VBC fiber assembly for delivering a beam having variablecharacteristics. In this example, there are three confinement regions2104, 2106, and 2108 and three barrier layers 2110, 2112, and 2116.Second length of fiber 2100 also has a plurality of divergencestructures 2114 and 2118. The divergence structures 2114 and 2118 areareas of graded lower index material. As the beam is launched from thefirst length fiber into second length of fiber 2100, refraction fromdivergence structures 2114 and 2118 causes the beam divergence toincrease. The amount of increased divergence depends on the amount ofspatial overlap of the beam with the divergence structure and themagnitude of the index difference between the divergence structure 2114and/or 2118 and the surrounding core material of confinement regions2106 and 2104 respectively. By adjusting the radial position of the beamnear the launch point into the second length of fiber 2100, thedivergence distribution may be varied. The design shown in FIG. 21allows the intensity distribution and the divergence distribution to bevaried somewhat independently by selecting both a particular confinementregion and the divergence distribution within that confinement region(because each confinement region may include a divergence structure).The adjusted divergence of the beam is conserved in fiber 2100, which isconfigured to deliver the adjusted beam to the process head, anotheroptical system, or the workpiece. Forming the divergence structures 2114and 2118 with a graded or non-constant index enables tuning of thedivergence profile of the beam propagating in fiber 2100. An adjustedbeam characteristic such as a radiance profile and/or divergence profilemay be conserved as it is delivered to a process head by the secondfiber. Alternatively, an adjusted beam characteristic such as a radianceprofile and/or divergence profile may be conserved or further adjustedas it is routed by the second fiber through a fiber-to-fiber coupler(FFC) and/or fiber-to-fiber switch (FFS) and to a process fiber, whichdelivers the beam to the process head or the workpiece.

FIGS. 26-28 are cross-sectional views illustrating examples of fibersand fiber RIPs configured to enable maintenance and/or confinement ofadjusted beam characteristics of a beam propagating in an azimuthallyasymmetric second length of fiber, wherein the beam characteristics areadjusted responsive to perturbation of a first length of fiber coupledto the second length of fiber and/or perturbation of the beam by aperturbation device 110. These azimuthally asymmetric designs are merelyexamples and are not an exhaustive recitation of the variety of fiberRIPs that may be used to enable maintenance and/or confinement ofadjusted beam characteristics within an azimuthally asymmetric fiber.Thus, claimed subject matter is not limited to the examples providedherein. Moreover, any of a variety of first lengths of fiber (e.g., likethose described above) may be combined with any azimuthally asymmetricsecond length of fiber (e.g., like those described in FIGS. 26-28).

FIG. 26 illustrates RIPs at various azimuthal angles of a cross-sectionthrough an elliptical fiber 2600. At a first azimuthal angle 2602, fiber2600 has a first RIP 2604. At a second azimuthal angle 2606 that isrotated 45° from first azimuthal angle 2602, fiber 2600 has a second RIP2608. At a third azimuthal angle 2610 that is rotated another 45° fromsecond azimuthal angle 2606, fiber 2600 has a third RIP 2612. First,second, and third RIPs 2604, 2608, and 2612 are all different.

FIG. 27 illustrates RIPs at various azimuthal angles of a cross-sectionthrough a multicore fiber 2700. At a first azimuthal angle 2702, fiber2700 has a first RIP 2704. At a second azimuthal angle 2706, fiber 2700has a second RIP 2708. First and second RIPs 2704 and 2708 aredifferent. In an example, perturbation device 110 may act in multipleplanes in order to launch the adjusted beam into different regions of anazimuthally asymmetric second fiber.

FIG. 28 illustrates RIPs at various azimuthal angles of a cross-sectionthrough a fiber 2800 having at least one crescent shaped core. In somecases, the corners of the crescent may be rounded, flattened, orotherwise shaped, which may minimize optical loss. At a first azimuthalangle 2802, fiber 2800 has a first RIP 2804. At a second azimuthal angle2806, fiber 2800 has a second RIP 2808. First and second RIPs 2804 and2808 are different.

FIG. 22A illustrates an example of a laser system 2200 including a VBCfiber assembly 2202 configured to provide variable beam characteristics.VBC fiber assembly 2202 comprises a first length of fiber 104, a secondlength of fiber 108, and a perturbation device 110. VBC fiber assembly2202 is disposed between feeding fiber 2212 (i.e., the output fiber fromthe laser source) and VBC delivery fiber 2240. VBC delivery fiber 2240may comprise second length of fiber 108 or an extension of second lengthof fiber 108 that modifies, maintains, and/or confines adjusted beamcharacteristics. Beam 2210 is coupled into VBC fiber assembly 2202 viafeeding fiber 2212. Fiber assembly 2202 is configured to vary thecharacteristics of beam 2210 in accordance with the various examplesdescribed above. The output of fiber assembly 2202 is adjusted beam2214, which is coupled into VBC delivery fiber 2240. VBC delivery fiber2240 delivers adjusted beam 2214 to a free-space optics assembly 2208,which then couples beam 2214 into a process fiber 2204. Adjusted beam2214 is then delivered to process head 2206 by process fiber 2204. Theprocess head can include guided wave optics (such as fibers and fibercoupler), free space optics (such as lenses, mirrors, optical filters,diffraction gratings), and/or beam scan assemblies (such as galvanometerscanners, polygonal mirror scanners, or other scanning systems) that areused to shape the beam 2214 and deliver the shaped beam to a workpiece.

In laser system 2200, one or more of the free-space optics of assembly2208 may be disposed in an FFC or other beam coupler 2216 to perform avariety of optical manipulations of an adjusted beam 2214 (representedin FIG. 22A with different dashing from that of beam 2210). For example,free-space optics assembly 2208 may preserve the adjusted beamcharacteristics of beam 2214. Process fiber 2204 may have the same RIPas VBC delivery fiber 2240. Thus, the adjusted beam characteristics ofadjusted beam 2214 may be preserved all the way to process head 2206.Process fiber 2204 may comprise a RIP similar to any of the secondlengths of fiber described above, including confinement regions.

Alternatively, as illustrated in FIG. 22B, free-space optics assembly2208 may change the adjusted beam characteristics of beam 2214 by, forexample, increasing or decreasing the divergence and/or the spot size ofbeam 2214 (e.g., by magnifying or demagnifying beam 2214) and/orotherwise further modifying adjusted beam 2214. Furthermore, processfiber 2204 may have a different RIP than VBC delivery fiber 2240.Accordingly, the RIP of process fiber 2204 may be selected to preserveadditional adjustment of adjusted beam 2214 made by the free-spaceoptics of assembly 2208 to generate a twice adjusted beam 2224(represented in FIG. 22B with different dashing from that of beam 2214).

FIG. 23 illustrates an example of a laser system 2300 including VBCfiber assembly 2302 disposed between a feeding fiber 2312 and a VBCdelivery fiber 2340. During operation, a beam 2310 is coupled into VBCfiber assembly 2302 via feeding fiber 2312. Fiber assembly 2302 includesa first length of fiber 104, a second length of fiber 108, and aperturbation device 110 and is configured to vary characteristics ofbeam 2310 in accordance with the various examples described above. Fiberassembly 2302 generates an adjusted beam 2314 output by VBC deliveryfiber 2340. VBC delivery fiber 2340 comprises a second length of fiber108 of fiber for modifying, maintaining, and/or confining adjusted beamcharacteristics in a fiber assembly 2302 in accordance with the variousexamples described above (see FIGS. 17-21, for example). VBC deliveryfiber 2340 couples adjusted beam 2314 into a beam switch (FFS) 2332,which then couples its various output beams to one or more of multipleprocess fibers 2304, 2320, and 2322. Process fibers 2304, 2320, and 2322deliver adjusted beams 2314, 2328, and 2330 to respective process heads2306, 2324, and 2326.

In an example, beam switch 2332 includes one or more sets of free-spaceoptics 2308, 2316, and 2318 configured to perform a variety of opticalmanipulations of adjusted beam 2314. Free-space optics 2308, 2316, and2318 may preserve or vary adjusted beam characteristics of beam 2314.Thus, adjusted beam 2314 may be maintained by the free-space optics oradjusted further. Process fibers 2304, 2320, and 2322 may have the sameor a different RIP as that of VBC delivery fiber 2340, depending onwhether it is desirable to preserve or further modify a beam passingfrom the free-space optics assemblies 2308, 2316, and 2318 to respectiveprocess fibers 2304, 2320, and 2322. In other examples, one or more beamportions of beam 2310 are coupled to a workpiece without adjustment, ordifferent beam portions are coupled to respective VBC fiber assembliesso that beam portions associated with a plurality of beamcharacteristics can be provided for simultaneous workpiece processing.Alternatively, beam 2310 can be switched to one or more of a set of VBCfiber assemblies.

Routing adjusted beam 2314 through any of free-space optics assemblies2308, 2316, and 2318 enables delivery of a variety of additionallyadjusted beams to process heads 2206, 2324, and 2326. Therefore, lasersystem 2300 provides additional degrees of freedom for varying thecharacteristics of a beam, as well as switching the beam between processheads (“time sharing”) and/or delivering the beam to multiple processheads simultaneously (“power sharing”).

For example, free-space optics in beam switch 2332 may direct adjustedbeam 2314 to free-space optics assembly 2316 configured to preserve theadjusted characteristics of beam 2314. Process fiber 2304 may have thesame RIP as that of VBC delivery fiber 2340. Thus, the beam delivered toprocess head 2306 will be a preserved adjusted beam 2314.

In another example, beam switch 2332 may direct adjusted beam 2314 tofree-space optics assembly 2318 configured to preserve the adjustedcharacteristics of adjusted beam 2314. Process fiber 2320 may have adifferent RIP from that of VBC delivery fiber 2340 and may be configuredwith divergence altering structures as described with respect to FIGS.20 and 21 to provide additional adjustments to the divergencedistribution of beam 2314. Thus, the beam delivered to process head 2324will be a twice adjusted beam 2328 having a different beam divergenceprofile from that of adjusted beam 2314.

Process fibers 2304, 2320, and/or 2322 may comprise a RIP similar to anyof the second lengths of fiber described above, including confinementregions or a wide variety of other RIPs, and claimed subject matter isnot limited in this regard.

In yet another example, free-space optics switch 2332 may directadjusted beam 2314 to free-space optics assembly 2308 configured tochange the beam characteristics of adjusted beam 2314. Process fiber2322 may have a different RIP from that of VBC delivery fiber 2340 andmay be configured to preserve (or alternatively further modify) the newfurther adjusted characteristics of beam 2314. Thus, the beam deliveredto process head 2326 will be a twice adjusted beam 2330 having differentbeam characteristics (due to the adjusted divergence profile and/orintensity profile) from those of adjusted beam 2314.

In FIGS. 22A, 22B, and 23, the optics in the FFC or FFS may adjust thespatial profile and/or divergence profile by magnifying or demagnifyingthe beam 2214 before launching into the process fiber. They may alsoadjust the spatial profile and/or divergence profile via other opticaltransformations. They may also adjust the launch position into theprocess fiber. These methods may be used alone or in combination.

FIGS. 22A, 22B, and 23 merely provide examples of combinations ofadjustments to beam characteristics using free-space optics and variouscombinations of fiber RIPs to preserve or modify adjusted beams 2214 and2314. The examples provided above are not exhaustive and are meant forillustrative purposes only. Thus, claimed subject matter is not limitedin this regard.

FIG. 24 illustrates various examples of perturbation devices, assembliesor methods (for simplicity referred to collectively herein as“perturbation device 110”) for perturbing a VBC fiber 200 and/or anoptical beam propagating in VBC fiber 200 according to various examplesprovided herein. Perturbation device 110 may be any of a variety ofdevices, methods, and/or assemblies configured to enable adjustment ofbeam characteristics of a beam propagating in VBC fiber 200. In anexample, perturbation device 110 may be a mandrel 2402, a micro-bend2404 in the VBC fiber, flexible tubing 2406, an acousto-optic transducer2408, a thermal device 2410, a piezo-electric device 2412, a grating2414, a clamp 2416 (or other fastener), or the like, or any combinationthereof. These are merely examples of perturbation devices 100 and notan exhaustive listing of perturbation devices 100, and claimed subjectmatter is not limited in this regard.

Mandrel 2402 may be used to perturb VBC fiber 200 by providing a formabout which VBC fiber 200 may be bent. As discussed above, reducing thebend radius of VBC fiber 200 moves the intensity distribution of thebeam radially outward. In some examples, mandrel 2402 may be stepped orconically shaped to provide discrete bend radii levels. Alternatively,mandrel 2402 may comprise a cone shape without steps to providecontinuous bend radii for more granular control of the bend radius. Theradius of curvature of mandrel 2402 may be constant (e.g., a cylindricalform) or non-constant (e.g., an oval-shaped form). Similarly, flexibletubing 2406, clamps 2416 (or other varieties of fasteners), or rollers250 may be used to guide and control the bending of VBC fiber 200 aboutmandrel 2402. Furthermore, changing the length over which the fiber isbent at a particular bend radius also may modify the intensitydistribution of the beam. VBC fiber 200 and mandrel 2402 may beconfigured to change the intensity distribution within the first fiberpredictably (e.g., in proportion to the length over which the fiber isbent and/or the bend radius). Rollers 250 may move up and down along atrack 2442 on a platform 2434 to change the bend radius of VBC fiber200.

Clamps 2416 (or other fasteners) may be used to guide and control thebending of VBC fiber 200 with or without a mandrel 2402. Clamps 2416 maymove up and down along a track 2442 or a platform 2446. Clamps 2416 mayalso swivel to change bend radius, tension, or direction of VBC fiber200. A controller 2448 may control the movement of clamps 2416.

In another example, perturbation device 110 may be flexible tubing 2406and may guide bending of VBC fiber 200 with or without a mandrel 2402.Flexible tubing 2406 may encase VBC fiber 200. Tubing 2406 may be madeof a variety of materials and may be manipulated using piezoelectrictransducers controlled by a controller 2444. In another example, clampsor other fasteners may be used to move flexible tubing 2406.

Micro-bend 2404 in VBC fiber is a local perturbation caused by lateralmechanical stress on the fiber. Micro-bending can cause one or both ofmode coupling and transitions from one confinement region to anotherconfinement region within a fiber, resulting in varied beamcharacteristics of the beam propagating in a VBC fiber 200. Mechanicalstress may be applied by an actuator 2436 that is controlled bycontroller 2440. For example, VBC perturbative device 110 can beconfigured to control in one axis or two axes the beam propagation pathin VBC fiber 200 by imparting at selected radial locations micro-bend2404 to VBC fiber 200. According to one embodiment, actuator 2436includes two actuator probes 2436 a and 2436 b positioned to applymechanical stress to VBC fiber 200 in orthogonal directions and therebydirect the beam propagating in VBC fiber 200 to any location in atwo-dimensional space. In other embodiments several azimuthallyspaced-apart probes (see e.g., FIG. 29, described later) are provided toapply force at discrete angles around a circumference so as to modify abeam propagation path. However, these are merely examples of methods forinducing mechanical stress in fiber 200 and claimed subject matter isnot limited in this regard. Skilled persons will appreciate that variousother techniques for beam steering are also suitable.

Acousto-optic transducer (AOT) 2408 may be used to induce perturbationof a beam propagating in the VBC fiber using an acoustic wave. Theperturbation is caused by the modification of the refractive index ofthe fiber by the oscillating mechanical pressure of an acoustic wave.The period and strength of the acoustic wave are related to the acousticwave frequency and amplitude, allowing dynamic control of the acousticperturbation. Thus, a perturbation assembly 110 including AOT 2408 maybe configured to vary the beam characteristics of a beam propagating inthe fiber. In an example, a piezo-electric transducer 2418 may createthe acoustic wave and may be controlled by a controller or driver 2420.The acoustic wave induced in AOT 2408 may be modulated to change and/orcontrol the beam characteristics of the optical beam in VBC 200 inreal-time. However, this is merely an example of a method for creatingand controlling an AOT 2408, and claimed subject matter is not limitedin this regard.

Thermal device 2410 may be used to induce perturbation of a beampropagating in VBC fiber using heat. The perturbation is caused by themodification of the RIP of the fiber induced by heat. Perturbation maybe dynamically controlled by controlling an amount of heat transferredto the fiber and the length over which the heat is applied. Thus, aperturbation assembly 110 including thermal device 2410 may beconfigured to vary a range of beam characteristics. Thermal device 2410may be controlled by a controller 2450.

Piezo-electric transducer 2412 may be used to induce perturbation of abeam propagating in a VBC fiber using piezoelectric action. Theperturbation is caused by the modification of the RIP of the fiberinduced by a piezoelectric material attached to the fiber. Thepiezoelectric material in the form of a jacket around the bare fiber mayapply tension or compression to the fiber, modifying its refractiveindex via the resulting changes in density. Perturbation may bedynamically controlled by controlling a voltage to the piezo-electricdevice 2412. Thus, a perturbation assembly 110 including piezo-electrictransducer 2412 may be configured to vary the beam characteristics overa particular range.

In an example, piezo-electric transducer 2412 may be configured todisplace VBC fiber 200 in a variety of directions (e.g., axially,radially, and/or laterally) depending on a variety of factors, includinghow the piezo-electric transducer 2412 is attached to VBC fiber 200, thedirection of the polarization of the piezo-electric materials, theapplied voltage, etc. Additionally, bending of VBC fiber 200 is possibleusing the piezo-electric transducer 2412. For example, driving a lengthof piezo-electric material having multiple segments comprising opposingelectrodes can cause a piezoelectric transducer 2412 to bend in alateral direction. Voltage applied to piezoelectric transducer 2412 byan electrode 2424 may be controlled by a controller 2422 to controldisplacement of VBC fiber 200. Displacement may be modulated to changeand/or control the beam characteristics of the optical beam in VBC 200in real-time. However, this is merely an example of a method ofcontrolling displacement of a VBC fiber 200 using a piezo-electrictransducer 2412 and claimed subject matter is not limited in thisregard.

Gratings 2414 may be used to induce perturbation of a beam propagatingin a VBC fiber 200. A grating 2414 can be written into a fiber byinscribing a periodic variation of the refractive index into the core.Gratings 2414 such as fiber Bragg gratings can operate as opticalfilters or as reflectors. A long-period grating can induce transitionsamong co-propagating fiber modes. The radiance, intensity profile,and/or divergence profile of a beam comprised of one or more modes canthus be adjusted using a long-period grating to couple one or more ofthe original modes to one or more different modes having differentradiance and/or divergence profiles. Adjustment is achieved by varyingthe periodicity or amplitude of the refractive index grating. Methodssuch as varying the temperature, bend radius, and/or length (e.g.,stretching) of the fiber Bragg grating can be used for such adjustment.VBC fiber 200 having gratings 2414 may be coupled to a stage 2426. Stage2426 may be configured to execute any of a variety of functions and maybe controlled by a controller 2428. For example, stage 2426 may becoupled to VBC fiber 200 with fasteners 2430 and may be configured tostretch and/or bend VBC fiber 200 using fasteners 2430 for leverage.Stage 2426 may have an embedded thermal device and may change thetemperature of VBC fiber 200.

FIG. 25 illustrates an example process 2500 for adjusting and/ormaintaining beam characteristics within a fiber without the use offree-space optics to adjust the beam characteristics. In block 2502, afirst length of fiber and/or an optical beam are perturbed to adjust oneor more optical beam characteristics. Process 2500 moves to block 2504,where the optical beam is launched into a second length of fiber.Process 2500 moves to block 2506, where the optical beam having theadjusted beam characteristics is propagated in the second length offiber. Process 2500 moves to block 2508, where at least a portion of theone or more beam characteristics of the optical beam are maintainedwithin one or more confinement regions of the second length of fiber.The first and second lengths of fiber may be comprised of the samefiber, or they may be different fibers.

Additive processes (e.g., powered jet or bed deposition) could bepreceded or followed by one or more of the following processes:drilling, hardening, marking, ablation, cladding, thermal (e.g., heat)treating, and cutting. A result of one such combination of processes isillustrated in a lower portion of FIG. 29, which shows an enlarged viewof a plateau region 2900 that has been deposited on a workpiece (e.g.,one or more of metals, metal alloys, polymers, ceramics, andcombinations thereof) using a laser beam 2910 exhibiting first beamcharacteristics 2920 (e.g., defining a large spot size having a higherBPP). A small trench 2926 has been subsequently cut into a flat top 2928of plateau region 2900 using laser beam 2910 exhibiting second beamcharacteristics 2930 (e.g., defining a small spot size having a lowerBPP).

By employing first beam characteristics 2920 to form plateau region2900, fewer passes of an otherwise narrower beam are needed. Conversely,by employing second beam characteristics 2930 to cut trench 2926, a moreprecise feature is formed than would have been possible with a widerbeam. Skilled persons will appreciate that there are many variations ofmulti-operation processes in which material is added during one processand removed or thermally treated during another process. Moreover, theterms multi-operation, multi-function, and multi-purpose are sometimesused as synonyms, but the term multi-operation is intended to be thebroadest term of the three. For example, multi-operation encompasses twoprocessing steps that might have the same function (e.g., back-to-backdeposition functions in which the latter of the two uses a refined BPPfor smaller features).

VBC techniques, such as those described previously, streamline theswitch between the aforementioned different beam characteristics thatfacilitate complementary laser process operations performed using asingle laser source. For example, FIG. 29 shows a multi-operationoptical beam delivery device 2950 to facilitate different laser processoperations by modification of beam characteristics of laser beam 2910.According to one embodiment, the different laser process operationsinclude laser deposition and pre- or post-processing of a depositionregion. A deposition region means any region that has been or will beprocessed, directly or indirectly, with an optical beam or depositionmedia applied by the optical beam to the region.

A laser source 2960 is employed to provide an optical beam that isadjustable by a beam characteristic conditioner 2964. According to oneembodiment, laser source 2960 and beam characteristic conditioner 2964define an all-in-fiber, waveguide delivered laser source 2968 configuredto manipulate beam characteristics along the lines described previouslyin this disclosure. In other words, laser source 2960 is afiber-delivered laser source including the all-in-fiber techniquesdescribed, among other places, with reference to FIGS. 4-10 formanipulating beam characteristics. In other embodiments, beamcharacteristics of an optical beam are modified by using free spaceoptics, a zoom lens, diffractive optical elements, multicore fiber, andother types of beam characteristic conditioners.

A delivery fiber 2970 coupled to, or otherwise forming an output fiberof, beam characteristic conditioner 2964 provides laser beam 2910 to aprocess head 2980 adapted for performing deposition functions as well aspre- or post-processing functions. Delivery fiber 2970 allows waveguidedelivered laser source 2968 to be spaced apart from process head 2980,which includes processing optics 2982 (explained later with reference toFIG. 30) and a multi-operation nozzle 2986 (explained later withreference to FIGS. 31-33).

FIG. 29 also shows a controller 2990 adapted to coordinate beamcharacteristics for the different processes. For example, controller2990 generates for mandrel 2402 (FIG. 24) signals indicating an amountof movement of mandrel 2402 that imparts a bend to fiber 200 so as tocontrol BPP based on the amount of bend, and thereby changes laser beam2910 from being configured for a deposition task to being configured forsome other processing task. Controller 2990, according to some otherembodiments, coordinates functions of beam characteristic conditioner2964 (e.g., mandrel 2402) with multi-operation nozzle 2986 that is thesubject of FIGS. 31-33. For example, controller 2990 optionallycoordinates one or more of deposition media feed rate, mass flow, gaspressure, mixing of gas composition, process speed, and switchingbetween ejecting gas or media from various orifices (see e.g., orificesshown in FIG. 32 or 33). Examples of types of controller hardwaresuitable for coordinating beam characteristic conditioner 2964, optionalmulti-operation nozzle 2986, and other optional equipment (such as anoptional zoom optic shown in FIG. 30) include mass flow controllers,programmable logic controllers (PLCs), and personal computer (PC)-basedcontroller hardware. For example, one type of mass flow controller,which could be modified to also control mandrel 2402 and perforce beamcharacteristics, is a Metco M1100C available from Oerlikon Metco ofPfäffikon, Switzerland.

FIG. 29 shows process head 2980 including a collimator lens 2992 and afocus lens 2996. Focus lens 2996 is typically not fixed inposition—being translatable along the vertical axis in FIG. 29—andcollimator lens 2992 is physically fixed in place. This configuration isreferred to as a so-called fixed optical configuration due to its fixedoverall magnification. In contrast, FIG. 30 shows a process head 3000supporting an optional zoom optic 3010, having a separate collimatinglens 3020 and focus lens 3024, to establish a so-called variable opticalconfiguration having a variable overall magnification. A variableoptical configuration is coordinated or synchronized with beamcharacteristic conditioner 2964 configurations to provide users with awider variety of available processes or modifiable process parameters.For example, according to some other embodiments, controller 2990establishes an initial function of beam characteristic conditioner 2964(e.g., mandrel 2402) defined by a first BPP, and then controller 2990refines that function based on a zoom level established by adjustingoptional zoom optic 3010 to refine power density applied to a workpiece.

FIG. 30 also shows another embodiment wherein separate single-functionnozzles are used in addition to or as an alternative to multi-operationnozzle 2986. For example, following an optional use of multi-operationnozzle 2986, a first single-purpose nozzle 3030 used for a firstdedicated function replaces multi-operation nozzle 2986. Then, a secondsingle-purpose nozzle 3034 is installed in place of the firstsingle-purpose nozzle 3030 for use with a second dedicated function thatis different, and so forth. Thus, a user or machine replaces nozzles inorder to perform various specialized deposition and pre- orpost-processing functions.

With respect to multi-operation nozzle 2986, FIGS. 31 and 32 show ingreater detail how process head 2980 (FIG. 29) is, according to oneembodiment, configured to perform a variety of functions includingproviding carrier gases, powder, or other media. For example,multi-operation nozzle 2986 includes multiple concentrically arrangedorifices 3100 (FIG. 31) for providing different materials. A centralorifice 3110 provides a pathway for laser beam 2910 and one or moregases deliverable at selectable pressures and flow rates (e.g., gasconfiguration A). An adjacent orifice 3120, which is radially displacedfrom and concentrically encompasses central orifice 3110, carries asecond gas that is deliverable at selectable pressures and flow rates(e.g., gas configuration B, optionally different from gas configurationA). In this example, gas configuration B carries powered media 3124. Athird orifice 3130 and a fourth orifice 3140 provide, respectively, athird gas configuration (e.g., gas configuration C) and a mixture of adifferent deposition media carried by a fourth gas configuration (e.g.,gas configuration D). Skilled persons will appreciate, however, that notall orifices need be employed, and some nozzles could have a greater orlesser number of orifices.

More generally, various other materials may controllably flow throughorifices of a multi-operation nozzle. Thus, materials broadly meansdeposition media (or simply, media) or gases used for material chemistrymodification or delivery of the material media (e.g. blown powder).Deposition media include wire, rod, strip, sheet, powder, slurry, orcombinations thereof. Gases include inert, active, oxidizing, nitriding,or combinations thereof.

FIG. 32 also shows a wire-feed site 3210 to controllably extend wire tobe laser deposited on a workpiece. Other nozzles may include one or moretubes for feeding wire or a strip-shaped tube. In other words, insteadof having a round port for a round feed wire, the port is shaped tomatch any shape of material to be deposited. For a strip, the shape ofthe port could be rectangular and sized to match material fed throughthe port, i.e., about 1 millimeter (mm)×0.2 mm.

FIG. 33 shows an end view of another multi-operation nozzle 3300 havingmutually azimuthally spaced apart orifices. According to one embodiment,a central orifice 3306 provides gas configuration A and a pathway forlaser beam 2910 (FIG. 29), a first set of orifices 3310 provides gasconfiguration B, a second set 3320 provides gas configuration C, and athird set 3330 provides gas configuration D. As described previously,some of the orifices may be dedicated to delivering gases at differentpressures or flows whereas other orifices could be dedicated todelivering deposition media. In some embodiments, beams from differentconfinement regions are deliverable to different orifices. Skilledpersons will also appreciate that the members of the sets need not bespaced apart in a radially symmetric manner. Also, in some embodiments,one or more orifices may even deliver wire through a tube for feed wireor a strip-shaped tube for strip, as described with reference to FIG.32.

Turning back to controller 2990, it is noted that each orifice or familyof orifices in a multi-operation nozzle may be independentlycontrollable. Also, multiple different sets may be controllable toprovide material contemporaneously, as in the case of orifices 3110 and3120 (FIG. 31), or at separate times, as in the case of the separatenozzles (FIG. 30).

The present inventors recognized that employing a zoom optic in aprocess head as a sole means to produce beam modifications also producespotentially undesirable reciprocal changes of both the spatial andangular distribution of the beam. In other words, a product of thevalues representing these distributions remains constant as the zoomoptic is adjusted, which is undesirable in some processes for reasonsset forth in the following paragraph. The reciprocal property of a zoomoptic stems from its inherent conservation of brightness asmodifications are made to the level of zoom. Thus, changing a spot sizeby a factor of two produces a reciprocal change in divergence, i.e., achange by a factor of one half, such that the product of values for spotsize and divergence generally remains constant irrespective of the levelof zoom. In processes that depend on certain divergence thresholds,these thresholds then constrain the spot size and vice versa.

A challenge for conventional multi-operation optical beam deliverydevices is that some processes expect a fairly tight tolerance in termsof divergence. For instance, to inhibit laser beam 2910 from damagingunderlying tooling or foundational material, a certain value ofdivergence is employed such that power begins to rapidly diminish aslaser beam 2910 propagates past its target. But if the spot size anddivergence are coupled (e.g., reciprocal), as in conventional zoom lenssystems, then an increase in spot size would reciprocally decreasedivergence and thereby concentrate power in a manner that jeopardizesthe underlying tooling surface as the spot size is adjusted fordifferent processes. More generally, a low tolerance for a change indivergence could, in some processes, constrain changes to the spatialdistribution.

Likewise, where a certain tolerance of spatial distributions is expected(e.g., to avoid under or overfilling optics), changes in divergencecould constrain changes to the spatial distribution. For example, oneapplication where it is advantageous to vary divergence without areciprocal change in spatial profile is cutting with depositionpost-processing. A laser beam at a first divergence angle is optimizedto initially pierce the metal. Then, once the laser beam has piercedthrough the metal, the divergence is changed to a second divergenceangle optimizing the beam for cutting. Another change is made tooptimize the beam for deposition during post-processing.

Beam characteristic conditioner 2964 has a capability of decouplingspatial and angular distributions of a beam. FIG. 29 shows a change inspatial distribution because a spot size of laser beam 2910 narrows tocut trench 2926, and this change in spatial distribution may be achievedwithout a reciprocal change in angular distribution, i.e., anon-reciprocal change. Thus, as the spot size is narrowed, thedivergence is largely maintained so that an interior portion of plateauregion 2900 is not inadvertently damaged.

In a theoretical case, spatial and angular distributions may becompletely decoupled and therefore varied independently. In practice,however, effects of cladding and other practical limitations result insubstantial (though not complete) decoupling. Stated another way, theproduct of the values representing spatial and angular distribution neednot remain constant as parameters are varied in response to an appliedperturbation.

Having described and illustrated the general and specific principles ofexamples of the presently disclosed technology, it should be apparentthat the examples may be modified in arrangement and detail withoutdeparting from such principles. We claim all modifications and variationcoming within the spirit and scope of the following claims.

The invention claimed is:
 1. A multi-operation optical beam deliverydevice to facilitate different laser process operations by modificationof beam characteristics of an optical beam, the different laser processoperations including laser deposition and processing of a depositionregion, the multi-operation optical beam delivery device comprising: alaser source to generate the optical beam; a beam characteristicconditioner that, in response to a control input indicating a changebetween the different laser process operations, controllably modifiesthe beam characteristics for a corresponding laser process operation ofthe different laser process operations, the beam characteristicconditioner including first and second lengths of fiber having,respectively, first and second refractive index profiles (RIPs), thefirst RIP enabling, in response to an applied perturbation, modificationof the beam characteristics to form an adjusted optical beam havingmodified beam characteristics, and the second RIP defined by multipleconfinement regions formed to confine, and situated to receive through afiber-coupling interface functionally directly coupling the first andsecond lengths of fiber, at least a portion of the adjusted optical beamwithin at least one of the multiple confinement regions; and a deliveryfiber having an input end coupled to the beam characteristic conditionerand an output end coupled to a process head for performing thecorresponding laser process operation.
 2. The multi-operation opticalbeam delivery device of claim 1, in which the beam characteristicconditioner includes: a first length of fiber through which the opticalbeam propagates and which has a first refractive index profile (RIP),the first RIP enabling, in response to an applied perturbation,modification of the beam characteristics to form an adjusted opticalbeam having modified beam characteristics; and a second length of fibercoupled to the first length of fiber and having multiple confinementregions defining a second RIP that is different from the first RIP, themultiple confinement regions arranged to confine at least a portion ofthe adjusted optical beam and generate from it, at an output of thesecond length of fiber, an adjustable spatial or angular distributionthat, in response to the applied perturbation, changes for facilitatingthe corresponding laser process operation.
 3. The multi-operationoptical beam delivery device of claim 1, in which the beamcharacteristics define spatial and angular distributions, and in whichthe beam characteristic conditioner is configured to modify the angulardistribution by a desired amount that is non-reciprocal to an amount ofchange in the spatial distribution.
 4. The multi-operation optical beamdelivery device of claim 1, in which the beam characteristics definespatial and angular distributions, and in which the beam characteristicconditioner is configured to change the spatial distribution by adesired amount that is non-reciprocal to an amount of change in theangular distribution.
 5. The multi-operation optical beam deliverydevice of claim 1, further comprising the process head having opticalcomponents arranged in a fixed optical configuration.
 6. Themulti-operation optical beam delivery device of claim 1, furthercomprising the process head having optical components arranged in avariable optical configuration.
 7. The multi-operation optical beamdelivery device of claim 1, in which the processing of the depositionregion includes one or more of addition of a secondary feature onto apreviously deposited primary feature, thermal treatment of workpiecematerial or material deposited thereon, and removal of workpiecematerial or material deposited thereon.
 8. The multi-operation opticalbeam delivery device of claim 1, in which the processing of thedeposition region includes pre-processing of workpiece material ormaterial deposited thereon.
 9. The multi-operation optical beam deliverydevice of claim 1, in which the processing of the deposition regionincludes post-processing of workpiece material or material depositedthereon.
 10. The multi-operation optical beam delivery device of claim1, further comprising a multi-operation deposition nozzle havingmultiple orifices configured to deliver different deposition materials,the different deposition materials including a first material and asecond material, the first material for delivery during a first laserprocess operation and the second material for delivery during a secondlaser process operation that is different from the first laser processoperation.
 11. The multi-operation optical beam delivery device of claim10, in which the different deposition materials include depositionmedia.
 12. The multi-operation optical beam delivery device of claim 11,in which the deposition media includes one or more of wire, rod, strip,sheet, powder, and slurry deposition media.
 13. The multi-operationoptical beam delivery device of claim 10, in which the differentdeposition materials include a gas.
 14. The multi-operation optical beamdelivery device of claim 13, in which the gas includes one or more ofinert, active, oxidizing, and nitriding gas.
 15. The multi-operationoptical beam delivery device of claim 13, in which the gas modifiesmaterial chemistry or assists in delivery of deposition media.
 16. Themulti-operation optical beam delivery device of claim 10, in which themultiple orifices include first and second orifices that areconcentrically arranged in the multi-operation deposition nozzle. 17.The multi-operation optical beam delivery device of claim 10, in whichthe multiple orifices include first and second orifices that aremutually azimuthally spaced apart.
 18. The multi-operation optical beamdelivery device of claim 10, further comprising a controller to producethe control input and coordinate the change between the different laserprocess operations with delivery of deposition materials associated withthe corresponding laser process operation.
 19. The multi-operationoptical beam delivery device of claim 1, in which the correspondinglaser process operation includes deposition of media on one or more ofmetals, metal alloys, polymers, ceramics, and combinations thereof. 20.The multi-operation optical beam delivery device of claim 1, in whichthe beam characteristics define spatial and angular distributions, andin which the beam characteristic conditioner is configured toselectively change the spatial distribution substantially independentlyfrom the angular distribution, the angular distribution substantiallyindependently from the spatial distribution, or both the spatial andangular distributions in a non-reciprocal manner to each other.
 21. Themulti-operation optical beam delivery device of claim 1, in which thefirst RIP is a waveguide configured to impart transverse displacement tothe optical beam in response to the applied perturbation.
 22. Themulti-operation optical beam delivery device of claim 1, in which thefirst length of fiber includes an input for receiving the optical beamfrom an input fiber.
 23. The multi-operation optical beam deliverydevice of claim 22, in which the first length of fiber includes anoutput fused to an input of the second length of fiber.
 24. Themulti-operation optical beam delivery device of claim 1, in which thefiber-coupling interface includes an index-matching material.
 25. Themulti-operation optical beam delivery device of claim 1, in which thefiber-coupling interface includes a splice.
 26. The multi-operationoptical beam delivery device of claim 1, in which the fiber-couplinginterface includes a fiber joint.
 27. The multi-operation optical beamdelivery device of claim 1, in which the fiber-coupling interfaceincludes a connector.
 28. The multi-operation optical beam deliverydevice of claim 1, in which the fiber-coupling interface maintains asubstantially unaltered operative relationship between the first andsecond RIPs.